High voltage arrester cutout



y 3, 1966 D. o. MISARE ET AL HIGH VOLTAGE ARRESTER CUTOUT Filed Oct. 16,1964 INVENTQRS: DONALD O. MISARE PHILIP C. HENRY mrqwQMemmQmd ig ATT'YS' customer standpoint.

United States Patent 3,249,719 HIGH VOLTAGE ARRESTER CUTOUT Donald 0.Misare, Riverside, Ill., and Philip C. Henry,

St. Petersburg, Fla., assignors to Joslyn Mfg. and Supp yCm, Chicago,Ill., a corporation of Illinois Filed Oct. 16, 1964, Ser. No. 404,229 7Claims. (Cl. 200-115) The present invention relates to a new andimproved combination high voltage arrester cutout and more particularly,the present invention is concerned with improved lightning protection ofsuch combination units.

Combination arrester cutout assemblies for use on high voltagetransmission'structure are commercially available. The combinationarrester cutout generally includes a dropout type fuse circuit adaptedto interrupt current faults, and a suitable, externally gapped lightningarrester connected to afford protection to the cutout. The lightningarrester commonly provided commercially in the combination arrestercutout is provided with a characteristic element connected serially withone or more internal isolating gaps which function to keep the mainportion of the transmission system voltage off the characteristicelement in the absence of surges. The characteristic element serves tobypass to ground the surge current resulting from abnormal line voltagesand to interrupt the flow of system follow current as soon as theabnormal condition has terminated. One such lightning arrester suitablefor use in the present invention is illustrated and described in theco-pending application of Edward H.

Yonkers, Serial No. 157,293, filed November 16, 1961,

on Valve Type Lightning Arrester, and assigned to thesame-assignee asthe present invention. The fuse cutout may also be of a type known inthe art and, more specifically, may be similar to the fused cutoutassembly more fully described in United States Patent 2,862,082

and assigned to the same assignee as the present invention.

In the type of commercial installation described above, difliculty hasbeen experienced in that if the lightning arrester fails, due'toabnormal load conditions such as excessive voltages or direct lightningstrikes, the arrester willfail and will afford no internal resistance toground. Accordingly, the only protection of the transmission linecomponent against an open short to the ground is afforded by theexternal gap formed in the lightning arrester system. Any smallover-voltage would be sufiicient to spark the external gap or to causedischarge in the gap, and the discharge would be sufiicient onover-voltages to cause continuous and repetitious blowing of thecomponent fuses. Not only is it necessary to afford fuse protection, butsuch repetitive line failures are undesirable from the It is difficultto detect such a failed lightning arrester so that replacement may bemade.

In another type of lightning protector system, the lightning arrester isserially connected with an explosive type disconnector between theexternal lead of the high voltage component and the ground. One suitabledisconnector is illustrated and disclosed in Riley Patent No. 3,100,246granted August 6, 1963 on aDisconnector, and assigned to the sameassignee as the present invention. The disconnector has adequate timedelay so that discharges through the lightning arrester unit, sufficientto cause failure of the lightning arrester, will thereafter explode thecharge and the disconnector and will consequently break to remove'thearrester from the electrical transmission circuit. Although such afailured arrester in a combination arrested cutout can be readilydetected, in the meantime the fuse cutout isaiforded no protectionwhatsoever by the arrester unit and subsequent overvoltage conditionsmay cause the fuse cutout to interrupt the'transmission line component.

3,249,719 Patented May 3, 1966 "ice Accordingly, it is an object of thepresent invention to provide an improved high voltage combinationarrester cutout which overcomes the above-mentioned difficulties.

A further object of the present invention is to provide a new andimproved high voltage combination arrester cutout.

A further object of the present invention is to provide a new andimproved high voltage combination arrester cutout unit which willprovide a visual indication of a failed arrester, and will additionallyprovide continued protection to the fuse cutout against lightning surgesduring the interim period between the failure of the arrester andreplacement thereof.

Further objects and advantages of the present invention will becomeapparent as the following description proceeds and the features ofnovelty which characterize the invention will be pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

In accordance with these and many other objects of the presentinvention, there is provided a combination arrester cutout unit for highvoltage distribution systems. The cutout is of the dropout type fuseassembly including an insulator having stationary terminal memberscarried at opposite ends thereof adapted for connection to high voltagecomponents of the transmission system, and a dropout-fuse tube having afuse link capable of interruption upon abnormal amperage faults andnormally electrically interconnecting the terminals. An externallygapped lightning arrester of the type having an insulating shell housinga characteristic element formed of valve material in series withinternal isolating gaps is connected to one terminal of the cutoutthrough an external gap structure to form an external atmosphericisolating gap betwen the lightning arrester and the fuse cutout. In

accordance with the present invention, an explosive type disconnector isconnected across the external gap. In one embodiment of the invention,the explosive disconnector is connected by means of prestressedresilient spring which is effective to snap free of the lightningarrester upon an explosive failure of the disconnector.

Advantageously a combination arrester cutout unit according to thepresent invention not only provides a ready visual indication of afailured arrester on the cutout, but additionally affords continuedprotection to the fuse cutout against lightning surges during theinterim period between the failure of the arrester and replacementthereof.

For a better understanding of the present invention, reference may behad to the accompanying drawing wherein:

FIGURE 1 is an elevational view of a combination.

arrester cutout unit according to the present invention; and

FIGURE 2 is a fragmentary view of the combination arrester cutout ofFIGURE 1, illustrated after a failure of the explosive disconnector.

Referring now to the drawings, there is illustrated a high voltagecombination :arrester cutout 10 including a dropout type fuse assembly11 and a lightning arrester 12. The fuse assembly 11 may be similar tothe fuse assembly more fully described in the aforementioned US. Patent2,862,082. Briefly, the fuse assembly 11 includes an elongated insulator13 supported by a suitable bracket 14 from a transmission linesuperstructure. Upper and lower stationary terminal members 15 and 16are carried at opposite ends of the insulator 13 for connection to thehigh voltage transmission line component. The lower terminal member 16is provided with a pair of trunnion supports in the form of hook members18 which are spaced apart and which are provided with overhangingportions 19. The upper terminal member 15 is also provided with asuitable trunnion portion 20. The upper and lower terminal members and16 are provided with suitable means for connection to a high voltagetransmission line.

A dropout fuse structure, generally illustrated at 25, includes a fusetube or cartridge 26 having a downwardly and rearwardly extending arm 27extending from the lower end thereof and provided with a cross-trunnion28 hooked in the hook members 18 to pivotally interconnect the fuse tube26 to the lower terminal member 16. The fuse structure further includesan upper terminal 30 adapted to hook or engage the trunnion portion 25)of the upper terminal member 15 to provide electrical contact with thefuse tube 26.

The fuse assembly 11 is provided with a suitable fuse link 32, the upperend of which is secured to the upper terminal 30. The lower end of thefuse line 32 extends through the open lower end of the fuse tube 26 andis secured to suitable spring structure 37 adapted to snap the fuse link32 out of the tube 26 upon rupture of the fuse link 32.

It is understood that the fuse link 26 will fail upon abnormal amperagefault such as continuous shorts to ground. However, the lightningarrester 12 discharges abnormal lightning surges to ground therebyprotecting with suitable internal isolating spark ga means within thehousing 42 and electrically connected serially between the terminals 43and 44. The lightning arrester 12 is supported on a bracket 48 supportedby the bracket 14. One terminal 44 is adapted to be connected to groundpotential. An external electrode 50 is electrically connected to theother terminal 43 and it is provided with an electrode portion 50aspaced apart from an opposed electrode 51 connected to the terminal 15to provide an external isolating spark gap 52. If desired, the externalelectrodes 50 and 51 may provide for adjustability of the length of theisolating gap 52 in a known manner.

In accordance with the present invention, the combination arrestercutout 10 additionally includes an explosive disconnector 54. Theexplosive disconnector 54 may be of the type described in and claimed inthe abovementioned Riley patent and, accordingly, need not be hereindescribed in detail. However, briefly, as best illustrated in FIGURE 3,a known explosive disconnector 20 includes a housing 55 having at oneend a thin, fracturable section 56. The disconnector 54 includes a firstterminal connected to one terminal 43 of the lightning arrester 18 andhaving a second terminal 58 connected to the upper terminal 15 of thefuse cutout assembly 11 by a suitable conductor 60. Additionally thedisconnector 54 includes a threaded second terminal 58. Seriallyconnected between the terminals of the disconnector within the housing55 is a suitable explosive material. The disconnector 54 has an adequatetime lag upon a destructive discharge through the lightning arresterunit 15 that the lightning arrester 15 would first fail, and thereafterthe explosive material in the disconnector 54 would explode, rupturingthe housing 55 along the line 56 and separating the terminals thereof.

It is understood that an explosive rupture of the disconnector 54 willdrive the terminal 58 and connected housing free of the lightningarrester 12 to break the circuit thereto. The normal stiffness of theconductor 60, made of copper or other suitable conducting material, willmaintain the disconnector 54 separated. However, if desired, in order tosnap the disconnector 54 free upon explosion of the material therein,the conductor 60 may be a pre-stressed leaf spring of electricallyconductive material. As illustrated, the spring conductor 60 has one endconnected to the terminal 58 of the explosive disconnector :and theother end connected to the terminal 15 of the fuse assembly.

From the above detailed description, the operation of the improvedcombination arrester cutout unit is believed clear. However, briefly, itwill be understood that the lightning arrester unit includes anexternally gapped lightning arrester 12 provided with an explosivedisconnector 54 connected to a high voltage lead 15 of the fuse cutoutby means of a suitable conductor 60. The conductor 60 and the explosivedisconnector 54 are serially connected across the external isolating gap52 of the lightning arrester 12. If a discharge occurs through thelightning arrester unit 12 of suflicient magnitude to cause failure ofthe lightning arrester 12, the lightning arrester 12 then acts as ashort and, with suitable time delay, the explosive material in theexplosive disconnector 54 will be fired, rupturing the explosivedisconnector 54 breaking the circuit through the disconnector. If theconductor 60 consists of a prestressed spring, the spring will aid insnapping the upper terminal 58 of the explosive disconnector 54 apartfrom the remainder of the disconnector. This provides a visualindication of a defective lightning arrester unit, as best illustratedin FIGURE 2. Advantageously the lightning arrester unit 12 according tothe present invention, continues to afford continued protection againstlightning surges during the interim period after failure and beforereplacement of the lightning arrester unit 12 due to the externalisolating spark gap 52. Although the lightning arrester unit 12 afterfiring of the explosive disconnector 54 affords reduced resistance toground which may result in occasional blowing of the component fuses,nevertheless adequate protection is afforded to prevent destruction ofthe high voltage system.

Although the present invention has been described by reference to asingle embodiment thereof, it will be apparent that numerous othermodifications and embodiments will be devised by those skilled in theart which will fall within the true spirit and scope of the presentinvention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A combination arrestor cutout unit for use with a high voltage powerdistribution system comprising: a dropout type fuse unit includingspaced cutout terminals and means including a fuse link capable ofinterruptions upon abnormal amperage faults and normally electricallyconnected across said terminals; a lightning arrester for passingabnormal voltage surges to ground; a pair of spaced apart spark gapterminals defining an external isolating gap; said lightning arresterand said gap being normally serially electrically connected betweenground and one of said cutout terminals; arrester disconnector meanselectrically connected to one of said spark gap terminals; andelectrical conducting means electrically connecting the other of saidspark gap terminals to said arrester disconnector means, said arresterdisconnector means explosively isolating said spark gap terminals fromone another upon an over voltage condition, said disconnector means andsaid electrical conducting means indicating a failure of the lightningarrester, said gap provid ing protection after isolating by saidarrester disconnector means.

2. The structure defined by claim 1 wherein the electrical conductingmeans connected across the gap comprises a deflectable member normallydisposed in a predetermined position in engagement with said arrestordisconnector means but deflectable to a different position in the eventof operation of said arrester disconnector means.

3. The structure defined by claim 1 wherein the lightg arrester and thefuse unit are carried upon a com- 5. mon support bracket which, in turn,is mountable upon at least one distribution system component.

4. A combination arrester cutout unit for use with a high voltage powerdistribution system comprising: a dropout type fuse unit including aninsulator and spaced cutout terminals carried by said insulator andadapted for connection to distribution components, a dropout fuse tubecarried by said insulator and having a fuse link capable ofinterruptions upon abnormal amperage faults and normally electricallyconnected across said terminals; bracket means adapted to support saidinsulator from a transmission system component; a lightning arrestermounted on said bracket for passing abnormal voltage surges to groundand being of the type having an insulating shell carrying spacedterminal means and housing a characteristic element in series with anisolating gap, said characteristic element being formed of valvematerial having a nonlinear resistance; a pair of spaced apart spark gapterminals defining an external isolating gap, said lightning arresterand said gap being normally serially electrically connected betweenground and one of said cutout terminals; arrester disconnector meanselectrically connected to one of said spark gap terminals; andelectrical conducting means electrically connecting the other of saidspark gap terminals to said arrester disconnector means, said arresterdisconnector means explosively isolating said spark gap terminals fromone another upon an over voltage condition, said disconnector means andsaid electrical conducting means indicating a failure of the lightningarrester, said gap providing protection after isolating by said arresterdisconnector means.

5. A combination arrester cutout unit for use with a high voltage powerdistribution system comprising: a dropout type fuse unit includingspaced cutout terminals and means including a fuse link capable ofinterruptions upon abnormal amperage faults and normally electricallyconnected across said terminals; a lightning arrester pro- 6 vided witha pair of spaced terminal means for passing abnormal voltage surges toground; a pair of spaced apart spark gap terminals defining an externalisolating gap; one of said spark gap terminals being electricallyconnected to one of said terminal means and the other of said spark gapterminals being electrically connected to one of said cutout terminals;the other of said terminal means being adapted normally to be seriallyelectrically connected to ground; arrester disconnector meanselectrically connected to one of said spark gap terminals; andelectrical conducting means electrically connecting the other of saidspark gap terminals to said arrester disconnector means, said arresterdisconnector means explosively isolating said spark gap terminals fromone another upon an over voltage condition, said disconnector means andsaid electrical conducting means indicating a failure of the lightningarrester, said gap providing protection after isolating by said arresterdisconnector means.

6. The structure defined by claim 5 wherein the electrical conductingmeans connected across the gap comprises a defiectable member normallydisposed in a predetermined position in engagement with said arresterdisconnector means but deflectable to a different position in the eventof operation of said arrester disconnector means.

7. The structure defined by claim 5 wherein the lightning arrester andthe fuse unit are carried upon a common support bracket which, in turn,is mountable upon at least one distribution system component.

References Cited by the Examiner UNITED STATES PATENTS 2,971,132 2/1961Nash 200-11s X 3,038,046 6/1961 Devine et a1. 200- X BERNARD A.GILHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner. I

1. A COMBINATION ARRESTOR CUTOUT UNIT FOR USE WITH A HIGH VOLTAGE POWERDISTRIBUTION SYSTEM COMPRISING: A DROPOUT TUPE FUSE UNIT INCLUDINGSPACED CUTOUT TERMINALS AND MEANS INCLUDING A FUSE LINK CAPABLE OFINTERRUPTIONS UPON ABNORMAL AMPERAGE FAULTS AND NORMALLY ELECTRICALLYCONNECTED ACROSS SAID TERMINALS; A LIGHTNING ARRESTER FOR PASSINGABNORMAL VOLTAGE SURGES TO GROUND; A PAIR OF SPACED APART SPARK GAPTERMINALS DEFINING AN EXTERNAL ISOLATING GAP; SAID LIGHTNING ARRESTERAND SAID GAP BEING NORMALLY SERIALLY ELECTRICALLY CONNECTED BETWEENGROUND AND ONE OF SAID CUTOUT TERMINALS; ARRESTER DISCONNECTOR MEANSELECTRICALLY CONNECTED TO ONE OF SAID SPARK GAP TERMINALS; ANDELECTRICAL CONDUCTING MEANS ELECTRICALLY CONNECTING THE OTHER OF SAIDSPARK GAP TERMINALS TO SAID